3850 is faster, but based on older technology and does not support DirectX 11. That being said, neither of them is actually a good fit for your system. I would replace this 3850 with Nvidia 750Ti, which is several times faster than 3850, while consuming 2x less power in the process.
EDIT: As for the Windows Experience Index, forget about it. This benchmark is far from being relevant for anything. If you want real benchmarks, try Unigine Haven / Valley, or 3DMark.
Thanks for reply friend. Yeah, i guess i should get new gpu. As now i am very short on money ( in my country prices for PC equipment are too high ) i am thinking of getting used HD7770 or HD7750 maybe but will check out prices for 750Ti, i am nvidia fan anyways